Grouting prestress lining experiment system and construction method thereof

Abstract

The invention discloses a grouting prestress lining experiment system and a construction method thereof. The system comprises a triaxial ground stress loading assembly, a model box, a grouting assembly and a tunnel structure. The model box is arranged in the triaxial ground stress loading assembly; the tunnel structure is arranged in the model box and further communicates with the grouting assembly. Each panel of the model box can slide, so that the volume of the accommodating cavity in the model box is adjustable; the triaxial ground stress loading assembly is used for applying stress in a preset direction to the tunnel structure through the model box so as to simulate actual stress of the tunnel structure; the tunnel structure comprises a lining, a surrounding rock layer and a grouting layer arranged between the lining and the surrounding rock layer, the grouting layer is formed after a grouting assembly injects a slurry material into a hollow annular grouting film bag to be solidified, and during grouting, the inner wall of the hollow annular grouting film bag is attached to the outer surface of the lining. The invention aims to accurately obtain the mechanical response of the lining test piece under different ground stress conditions.

Description

Technical Field

[0001] The invention relates to the technical field of grouting prestressed lining equipment, and in particular to a grouting prestressed lining experimental system and a construction method thereof. Background Art

[0002] At present, pressurized concrete tunnels mainly include water conveyance tunnels and high-pressure gas storage tunnels. The lining structures of these tunnels will produce tensile strain under the action of high internal pressure, causing lining cracking and affecting project safety. In order to solve the safety problem of pressurized tunnel linings and improve their ultimate internal pressure bearing capacity, grouting prestressed lining structure technology is currently used to achieve this. The principle of this technology is: high-pressure grouting is used to squeeze the lining body between the reinforced concrete lining and the surrounding rock, and compressive stress is given to the lining in advance to balance the tensile stress applied by the internal high-pressure water or high-pressure gas, thereby improving the ultimate internal pressure bearing capacity of the lining and reducing lining cracking. The grouting prestressed lining structure has advantages in waterproofing, durability and bearing performance, and has been initially applied to pressurized water conveyance tunnel projects.

[0003] At the same time, there are corresponding disclosures in indoor tests. For example, the invention patent with patent publication number CN113832903A discloses that the present invention discloses a water-mechanical coupling test method for the bearing system of tunnel surrounding rock and lining structure, including the following steps: casting lining structure and surrounding rock layer with the same height and flush end faces; installing a prestressed loading mechanism for steel strands with equal surrounding rock pressure; vertically hoisting the whole formed by the lining structure and the surrounding rock layer together with the prestressed steel strands wrapped around the periphery of the surrounding rock layer and connected at both ends into the inner cavity of the reaction wall; installing and sealing the upper cover plate; installing an external water pressure loading mechanism; external water pressure loading; data collection, and collecting and post-processing the collected stress and strain, prestressed steel strands applying surrounding rock pressure, external water pressure and other data through data collection software. Although this method can simulate the stress characteristics and related deformation characteristics of tunnel surrounding rock and water supply tunnel lining structure under complex external loads and equal surrounding rock pressure in actual environment, and can analyze and study the damage form of lining structure and crack distribution after cracking. However, the entire structural setting is relatively complicated, and the collected data is affected by other factors, resulting in low accuracy. Therefore, there is an urgent need to propose a device with simple structural setting, low cost and high accuracy. Summary of the invention

[0004] The main purpose of the present invention is to provide a grouting prestressed lining test system and a construction method thereof, aiming to solve the technical problems that the existing simulation test device has a complex structure and the data obtained is not accurate enough.

[0005] To achieve the above-mentioned object, the present invention provides a grouting prestressed lining experimental system, wherein the system comprises a triaxial geostress loading component, a model box, a grouting component and a tunnel structure;

[0006] The model box is arranged in a triaxial geostress loading assembly;

[0007] The tunnel structure is arranged in the model box and is also connected to a grouting assembly, and the grouting assembly is used to inject slurry material into the tunnel structure;

[0008] The panels of the model box are slidable so that the volume of the accommodating cavity in the model box can be adjusted;

[0009] The triaxial geostress loading assembly is used to apply a preset directional stress to the tunnel structure through the model box to simulate the actual stress of the tunnel structure;

[0010] The tunnel structure includes a lining, a surrounding rock layer and a grouting layer arranged between the lining and the surrounding rock layer. The grouting layer is formed by a grouting assembly that injects slurry material into a hollow annular grouting membrane bag and solidifies it. During grouting, the inner wall of the hollow annular grouting membrane bag is attached to the outer surface of the lining.

[0011] Optionally, the hollow annular grouting membrane bag is made of elastic rubber material.

[0012] Optionally, the grouting assembly includes a movable base plate, a grouting material barrel disposed on the base plate, a pressure pump, and a grouting pipe connecting the grouting material barrel and the hollow annular grouting membrane bag, wherein the grouting pipe is connected to the pressure pump.

[0013] Optionally, a plurality of pressure sensing patches are arranged between the surrounding rock layer and the grouting layer.

[0014] Optionally, a plurality of annular and radial pressure sensing patches are arranged on the outer surface of the lining.

[0015] Optionally, both ends of the lining are respectively installed in the corresponding grooves of the flanges, and one of the flanges is also provided with a reserved opening for the hollow annular grouting membrane bag to pass through.

[0016] Optionally, the inner diameter of the hollow annular grouting membrane bag is the same as the outer diameter of the lining.

[0017] Optionally, the lining is cast using a lining casting mould.

[0018] In addition, in order to achieve the above-mentioned purpose, the present invention also provides a construction method of a grouting prestressed lining experimental system, the method comprising the following steps:

[0019] Step 1, preparing lining specimens;

[0020] Step 2, installing corresponding flanges on the front and rear plates of the model box, and nesting the hollow annular grouting membrane bag on the periphery of the lining, then installing the lining specimen into the corresponding flange groove, and passing the grouting inlet section of the hollow annular grouting membrane bag through the grouting reserved opening of the front flange, and finally filling the model box and the outside of the hollow annular grouting membrane bag with surrounding rock materials to form a surrounding rock layer, wherein a preset number of patch stress sensors are pasted on the outer surface of the hollow annular grouting membrane bag, and the sensors are connected to the electrical signals of the external monitoring component;

[0021] Step 3, adjust the pressure pump to the preset pressure value, then inject slurry material into the hollow annular grouting membrane bag, monitor the slurry pressure in the membrane bag in real time, and close the slurry stop valve at the grouting inlet of the hollow annular grouting membrane bag until the set value is reached, and wait for the slurry to solidify, and finally form a geological model of lining-grouting layer-surrounding rock;

[0022] Step 4: input preset geostress data into the loading control center of the triaxial geostress loading assembly. When the loading cylinder is loaded to the preset geostress, keep applying the current force stably and keep the preset holding time, and record the collected stress-strain data. The preset geostress data mainly includes horizontal and vertical geostress values ​​and holding time.

[0023] Step 5: Export and analyze the data recorded by the sensor throughout the process, and analyze the stress-strain data during the curing of the grouting layer to obtain the mechanical response of the lining specimen under different ground stress conditions.

[0024] Optionally, the step 1 specifically includes: pre-welding and welding a target steel mesh with circumferential and radial steel bars, fixing strain gauges on the circumferential steel bars, and welding a compressed air sensor box on the axial steel bars, so as to collect circumferential and axial stress and strain data on the steel mesh during the test;

[0025] After the sensors are laid out, the steel mesh is placed in the center of the lining casting mold and the mixed concrete is poured in. After the casting is completed and the mold is removed after curing and forming, strain gauges are posted on the outside of the reinforced concrete lining in the circumferential and axial directions.

[0026] Beneficial effects:

[0027] The system of the present invention adopts a reasonable combination of triaxial geostress loading components, tunnel structures, and grouting components to achieve full grouting process simulation under controllable geostress conditions, with high restoration and small test errors. The grouting membrane bag design is introduced to create a flexible cavity between the lining and the surrounding rock in advance to provide grouting space. This design ensures that the high-pressure grouting slurry pressure fully squeezes the lining and surrounding rock while preventing the slurry from splashing everywhere, which is conducive to the smooth extrusion of the lining to apply prestress, and at the same time forms an ideal grouting layer with a more regular shape and a more uniform texture, restoring the high-pressure grouting scenario in real engineering, thereby improving the accuracy of the experiment. In addition, the actual construction process of the system is also simple, convenient, and low-cost, which can be easily promoted and applied. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural schematic diagram of an embodiment of a grouting prestressed lining experimental system of the present invention;

[0029] Figure 2 for Figure 1 Schematic diagram of the structure of the hollow annular grouting membrane bag before and after grouting;

[0030] Figure 3 This is a schematic diagram of the lining casting mold;

[0031] Figure 4 Schematic diagram of the structure of the lining after pouring.

[0032] Figure 5 for Figure 1 Physical diagram of the distribution of lining-grouting layer-surrounding rock layer after grouting is completed.

[0033] Description of Figure Numbers:

[0034] 1 triaxial geostress loading assembly, 2 model box, 21 lining, 22 grouting layer, 23 surrounding rock layer, 31 sliding bottom plate, 32 grouting material barrel, 33 pressure pump, 34 grouting pipe

[0035] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0036] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0037] See also Figures 1 to 5The present invention provides a grouting prestressed lining experimental system, the system comprises a triaxial geostress loading component 1, a model box 2, a grouting component and a tunnel structure; the model box 2 is arranged in the triaxial geostress loading component 1; the tunnel structure is arranged in the model box 2, and in the system preparation construction state, the tunnel structure is also connected with the grouting component; each panel of the model box 2 can slide so that the volume of the accommodating cavity in the model box 2 can be adjusted; wherein the triaxial geostress loading component 1 is a hydraulic cylinder with three axial directions of xyz, such as Figure 1 As shown in the figure, the four surfaces (left surface, right surface, upper surface and rear surface) of the model box 2 are subjected to stress from hydraulic cylinders in three directions. Each hydraulic cylinder is started and stopped by a controller. Preferably, each controller is integrated in a corresponding loading control component.

[0038] like Figure 2 , 5 As shown, the tunnel structure includes a lining 21, a surrounding rock layer 23 and a grouting layer 22 arranged between the lining 21 and the surrounding rock layer 23. The grouting layer 22 is formed by a grouting assembly by injecting slurry material into a hollow annular grouting membrane bag and solidifying it. During grouting, the inner wall of the hollow annular grouting membrane bag is attached to the outer surface of the lining 21, and the surrounding rock layer 23 is filled outside the grouting layer 22 in the model box 2. The surrounding rock material layer is made of sand, gypsum, fly ash, etc. in a certain proportion to simulate the real stratum.

[0039] The triaxial geostress loading assembly 1 is used to apply preset directional stress to the tunnel structure through the model box 2 to simulate the actual stress of the tunnel structure, and then obtain the mechanical response of the lining specimen under different geostress conditions.

[0040] Furthermore, the hollow annular grouting membrane bag is made of elastic rubber material. The inner diameter of the hollow annular grouting membrane bag is the same as the outer diameter of the lining 21, so that the hollow annular grouting membrane bag is just sleeved on the periphery of the lining 21, and a grouting space for the grouting layer 22 is formed in the membrane bag, thereby avoiding the problem of subsequent splashing and leakage of high-pressure slurry.

[0041] Furthermore, the grouting assembly includes a movable bottom plate 31, a grouting material barrel 32 disposed on the bottom plate 31, a pressure pump 33, and a grouting pipe 34 connecting the grouting material barrel 32 and the hollow annular grouting membrane bag, and the grouting pipe 34 is connected to the pressure pump 33. The pressure of the pressure pump 33 is adjustable, so that grouting can be performed between the surrounding rock layer 23 and the lining 21 according to a specified flow rate until a preset pressure is reached. The bottom plate 31 is movable, so that the grouting assembly is movable as a whole, which is convenient for transportation.

[0042] Furthermore, a plurality of pressure sensing patches are provided between the surrounding rock layer 23 and the grouting layer 22, so as to obtain the stress data between the surrounding rock layer 23 and the grouting layer 22 under stress loading.

[0043] Furthermore, a plurality of circumferential and radial pressure sensing patches are arranged on the outer surface of the lining 21, so as to obtain the force data between the lining 21 and the grouting layer 22 under stress loading.

[0044] Furthermore, both ends of the lining 21 are respectively installed in the corresponding grooves of the flanges, and one of the flanges is also provided with a reserved opening for the hollow annular grouting membrane bag to pass through.

[0045] Further, the lining 21 is cast by using a lining casting mold. In actual application, the lining 21 is cast by using a lining casting mold.

[0046] In addition, in order to achieve the above-mentioned purpose, the present invention also provides a construction method of a grouting prestressed lining experimental system, the method comprising the following steps:

[0047] Step 1: Prepare lining specimens; specifically, cast the chamber lining model according to the test requirements, and cast the mold as follows: Figure 3 As shown in the figure, its metal outer wall and inner wall are vertically installed on the base card slot to form a hollow cylindrical chamber, and a pre-woven steel mesh is placed in the chamber, wherein the steel mesh is pre-woven and welded into a target steel mesh with annular and radial steel bars, and a strain gauge is fixed on the annular steel bar and a compressed air sensor box is welded on the axial steel bar to collect the annular and axial stress and strain data on the steel mesh during the test; after the sensor is arranged, the steel mesh is placed in the center of the lining casting mold, and the mixed concrete is injected. After the casting is completed, the mold is removed after curing and forming, and strain gauges are posted on the outside of the reinforced concrete lining along the annular and axial directions. The sample-prepared reinforced concrete lining is as shown in the figure. Figure 4 shown.

[0048] Step 2: Install the corresponding flanges on the front and rear plates of the model box, and nest the hollow annular grouting membrane bag on the periphery of the lining, then install the lining specimen into the corresponding flange groove, and pass the grouting inlet section of the hollow annular grouting membrane bag through the grouting reserved opening of the front flange, and finally fill the model box and the hollow annular grouting membrane bag with surrounding rock materials to form a surrounding rock layer, wherein a preset number of patch stress sensors are pasted on the outer surface of the hollow annular grouting membrane bag, and the sensors are connected to the electrical signals of the external monitoring components; and before grouting, check whether all monitoring signals such as pressure, strain, and stress sensors are normal. Grouting starts after the monitoring equipment is normal.

[0049] Step 3, add enough grouting slurry material into the grouting material barrel in the grouting assembly to ensure that the slurry height in the container is above the grouting pipe and no air is pumped in. Adjust the pressure pump to the preset pressure value, then inject the slurry material into the hollow annular grouting membrane bag, and monitor the slurry pressure in the membrane bag in real time until it reaches the set value, then close the stop valve at the grouting inlet of the hollow annular grouting membrane bag to wait for the slurry to solidify, and finally form a geological model of lining-grouting layer-surrounding rock layer; the solidification time of the grouting layer is generally 20-30 minutes.

[0050] Step 4, input the preset geostress data into the loading control component of the triaxial geostress loading component, and start loading. When the loading cylinder is loaded to the preset geostress, keep applying the current force stably and keep the preset holding time, and record the collected stress-strain data. The preset geostress data mainly includes horizontal and vertical geostress values ​​and holding time.

[0051] Step 5: Export and analyze the data recorded by the pressure, strain and stress sensors throughout the process, and analyze the stress-strain data during the curing of the grouting layer to obtain the mechanical response of the lining specimen under different ground stress conditions. Then, obtain the mechanism of prestressing in the high-pressure grouting extrusion lining.

[0052] The above construction method adopts a reasonable combination of triaxial geostress loading components, tunnel structure, and grouting components to achieve full-process simulation of grouting under controllable geostress conditions, with high restoration degree and small experimental error.

[0053] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or system. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or system including the element.

[0054] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0055] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A grouting prestressed lining test system, characterized in that: The system comprises a triaxial geostress loading component (1), a model box (2), a grouting component and a tunnel structure; The model box (2) is arranged in the triaxial geostress loading component (1); The tunnel structure is arranged in the model box (2) and is also connected to a grouting assembly, and the grouting assembly is used to inject slurry material into the tunnel structure; The panels of the model box (2) are slidable so that the volume of the accommodating cavity in the model box (2) can be adjusted; The triaxial geostress loading assembly (1) is used to apply a preset directional stress to the tunnel structure through the model box (2) to simulate the actual stress on the tunnel structure; The tunnel structure comprises a cylindrical lining (21), a surrounding rock layer (23) and a grouting layer (22) arranged between the lining (21) and the surrounding rock layer (23); the grouting layer (22) is formed by a grouting assembly by injecting slurry material into a hollow annular grouting membrane bag and then solidifying it; during grouting, the inner wall of the hollow annular grouting membrane bag is attached to the outer surface of the lining (21).

2. The grouting prestressed lining test system according to claim 1, characterized in that: The hollow annular grouting membrane bag is made of elastic rubber material.

3. The grouting prestressed lining test system according to claim 1, characterized in that: The grouting assembly comprises a movable base plate (31), a grouting material barrel (32) arranged on the base plate (31), a pressure pump (33), and a grouting pipe (34) connecting the grouting material barrel (32) and the hollow annular grouting membrane bag, wherein the grouting pipe (34) is connected to the pressure pump (33).

4. The grouting prestressed lining test system according to claim 1, characterized in that: A plurality of pressure sensing patches are also arranged between the surrounding rock layer (23) and the grouting layer (22).

5. The grouting prestressed lining test system according to claim 1, characterized in that: A plurality of pressure sensing patches are arranged in annular and radial directions on the outer surface of the lining (21).

6. The grouting prestressed lining test system according to claim 1, characterized in that: The two ends of the lining (21) are respectively installed in the corresponding grooves of the flanges, and one of the flanges is also provided with a reserved opening for the hollow annular grouting membrane bag to pass through.

7. The grouting prestressed lining test system according to claim 1, characterized in that: The inner diameter of the hollow annular grouting membrane bag is the same as the outer diameter of the lining (21).

8. The grouting prestressed lining test system according to any one of claims 1 to 7, characterized in that: The lining (21) is cast using a lining casting mould.

9. A construction method for a grouting prestressed lining experimental system, characterized in that: The method The following steps are included: Step 1, preparing lining specimens; Step 2, installing corresponding flanges on the front and rear plates of the model box, and nesting the hollow annular grouting membrane bag on the periphery of the lining, then installing the lining specimen into the corresponding flange groove, and passing the grouting inlet section of the hollow annular grouting membrane bag through the grouting reserved opening of the front flange, and finally filling the model box and the outside of the hollow annular grouting membrane bag with surrounding rock materials to form a surrounding rock layer, wherein a preset number of patch stress sensors are pasted on the outer surface of the hollow annular grouting membrane bag, and the sensors are connected to the electrical signals of the external monitoring component; Step 3, adjust the pressure pump to the preset pressure value, then inject slurry material into the hollow annular grouting membrane bag, monitor the slurry pressure in the membrane bag in real time, and close the slurry stop valve at the grouting inlet of the hollow annular grouting membrane bag until the set value is reached, and wait for the slurry to solidify, and finally form a geological model of lining-grouting layer-surrounding rock layer; Step 4: input preset geostress data into the loading control center of the triaxial geostress loading assembly. When the loading cylinder is loaded to the preset geostress, keep applying the current force stably and keep the preset holding time, and record the collected stress-strain data. The preset geostress data mainly includes horizontal and vertical geostress values ​​and holding time. Step 5: Export and analyze the data recorded by the sensor throughout the process, and analyze the stress-strain data during the curing of the grouting layer to obtain the mechanical response of the lining specimen under different ground stress conditions.

10. The construction method of the grouting prestressed lining test system according to claim 9, characterized in that: The step 1 specifically includes: pre-welding and welding a target steel mesh with circumferential and radial steel bars, fixing strain gauges on the circumferential steel bars, and welding a compressed air sensor box on the axial steel bars to collect circumferential and axial stress and strain data on the steel mesh during the test; After the sensors are laid out, the steel mesh is placed in the center of the lining casting mold and the mixed concrete is poured in. After the casting is completed and the mold is removed after curing and forming, strain gauges are posted on the outside of the reinforced concrete lining in the circumferential and axial directions.

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